Specialized metallurgical processes – compositions for use therei – Processes – Free metal or alloy reductant contains magnesium
Patent
1975-02-24
1976-06-01
Ozaki, G.
Specialized metallurgical processes, compositions for use therei
Processes
Free metal or alloy reductant contains magnesium
75 83, 423 42, C22B 1104
Patent
active
039605507
ABSTRACT:
The disclosure relates to a method for reclaiming silver from photographic substrates and particularly a method wherein silver halide coated substrates, such as plastic film, is subjected to a bleach solution for removing the silver bearing emulsion from the substrates the emulsion it is then placed in a settling tank and subjected to the use of sodium hydroxide and a flocculating agent, such that the sodium hydroxide acts to precipitate the silver, while the flocculating agent tends to flocculate it. Then removing the silver sludge from the lower strata of the settling tank and placing it in canvas bags to allow liquids to drain from the sludge while the flocculating agent retains the sludge in the bags. The sludge then dries to a substantially mud like consistency and then the silver sludge, of mud like consistency, is placed in an oven and heated, until the moisture thereof is released, and thereby rendering the mud like sludge dry and in a substantially hard cake like form. Then the hard cake like silver material is pulverized and placed in a crucible with a flux on top; the flux consisting of sodium carbonate and boric acid granules. The crucible is then subjected to heat sufficient to melt the silver out of the pulverized cake. Then the molten silver is poured in a first crucible and thereby forms a silver casting which is a primary casting. These primary castings may be then positioned in a second crucible with charcoal on the upper surface thereof, whereupon the primary castings are remelted, and whereupon the charcoal on top of the molten silver absorbs impurities, and then the molten silver is poured into a second casting of high purity.
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patent: 2643108 (1953-06-01), Lieberman
patent: 3418237 (1968-12-01), Booth et al.
patent: 3451788 (1969-06-01), Smith
patent: 3594157 (1971-07-01), Hendrickson et al.
patent: 3647422 (1972-03-01), Wainer
patent: 3660079 (1972-05-01), Govani
patent: 3748123 (1973-07-01), Bakker
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